Ze Text Adventure game Builder : Create as you play !
2D Game Engine
Modern 3D engine and IDE written using C# and C++.
Portable game engine with main focus on point-and-click adventures
C/C++ , PHP, PYTHON, 3D ENGINES, CHROME NATIVE CLIENT
3D .NET engine for Windows, Linux, Mac
XNA based game engine completely written in c#
Open source network game service
Investigo - DX9 Performance and Debugging Toolkit